1. Field of the Invention
The present invention relates to a battery module, and more particularly, to a battery module capable of holding partition walls at fixed installation positions and enhancing an engaging force of the unit batteries within a case.
2. Related Art
Generally, secondary batteries are rechargeable and can be repeatedly used. In particular, secondary batteries including only one battery cell are mainly used for various small portable electronic apparatuses, such as cellular phones, laptop computers, cameras, and camcorders. High-capacity secondary batteries (hereinafter referred to as a ‘battery module’) are formed by connecting a plurality of battery cells (hereinafter referred to as ‘unit batteries’), and are mainly used as power sources for driving motors, such as, for example, motors for hybrid electric vehicles (HEVs), electrical vehicles (EVs), and the like.
Each of the unit batteries constituting the battery module includes: an electrode assembly having a positive plate, a negative plate, and a separator serving as an insulator interposed therebetween, a case having a space for accommodating the electrode assembly, a cap assembly combined with the case to tightly close the case, and positive and negative terminals protruding from the cap assembly and electrically connected to the positive plate and the negative plate, respectively.
Further, when the respective unit batteries are generally prismatic batteries, a positive terminal and a negative terminal of one unit battery protruding upward from the cap assembly are arranged so as to alternate with a positive terminal and a negative terminal of another unit battery adjacent to the one unit battery, and a conductor is connected between the threaded positive and negative terminals to be fixed thereto with nuts, thereby forming a battery module.
Since the battery module is constructed by connecting several or tens of unit batteries to each other, the battery module has a problem in that its overall volume is increased because the typical battery module needs a cooling structure, a safety means, a system circuit, etc., which are adapted to be easily capable of radiating heat generated in each unit battery.
In order to solve the problem, a method of reducing the size of the battery module by reducing the interval between the unit batteries is used, but this causes another problem in that it is difficult to radiate the heat generated in the unit batteries.
Thus, a structure capable of easily radiating the heat generated in respective unit batteries as well as being capable of minimizing the volume of a battery module at the time of designing the battery module is needed. If the heat generated in the respective unit batteries cannot be efficiently radiated, this will increase the temperature which will result in malfunction of apparatuses to which the battery module is applied.
Particularly, it is of primary importance to radiate heat in high-output and high-capacity battery modules for HEVs, EVs, and the like. If the size of the battery modules is increased, there is a problem in that not only the weight of the battery modules increases but also the design of the apparatuses (particularly, vehicles) equipped with the battery modules becomes complex.
Therefore, the development of battery modules capable of improving heat radiation characteristics while minimizing their size in battery modules required to have high output and high capacity becomes significant in modern battery practice.
Also, in a conventional battery module, spaces are provided between respective unit batteries for circulation of cooling air. Partition walls are installed for preventing structural deformation of the unit batteries. End plates are installed at opposite ends of the battery module. The unit batteries and the partition walls are supported by fixing the end plates using elongated restraint rods.
However, such a conventional battery module has problems in that, when an external force is applied, nonuniform deformation may occur in the battery module, which may lower reliability of the battery module, making it difficult to hold installation positions of the partition walls (interval between the partition walls) constant, and to prevent positional movement of the unit batteries.